JOHANNESBURG (AFP) - South Africa was hit Saturday by a second running day of massive power cuts, as state-owned utility Eskom imposed the biggest rolling blackouts in almost seven years to keep its overstrained system from collapsing entirely.

Road traffic was disrupted as stoplights were affected, and not only homes but shopping centres too were intermittently out of power.

"We have a lot of generation plants out of service because of technical faults and we also have constraints on our diesel power stations in terms of fuel delivery," Eskom spokesman Andrew Etzinger said, adding the cuts will last until 2000 GMT on Saturday (8am Singapore time on Sunday).

It is the first time since 2008 the company has unleashed level three power cuts, which are the second most severe on Eskom's scale.

South Africa's power crisis in 2008 had forced its mines shut for days, cost the country billions of dollars and led to a sell off in the rand and investment outflow.

Since then rates have skyrocketed in an effort to provide the utility with the cash it needs to upgrade a system which is frequently at capacity.

However, the company was still not generating sufficient revenues to overhaul its network.

In order to help manage the power shortage, Eskom has asked users to cut their consumption by 10 per cent.

Power shortage is regularly cited as one of the weaknesses hampering South Africa's growth.

Africa's second biggest economy is expected to expand by just 1.4 per cent this year.

South Africa plans to build nuclear power plants, adding to the one it has in Koeberg, but the proposal has sparked controversy due to its cost.